Loose wiring or electrical connections can start electrical fires, causing loss of life and property. An intermittent or loose connection has a higher electrical resistance than a proper connection. When current flows through the connection, excess heat is generated at the connection point, potentially creating a fire hazard. In addition, an intermittent connection can also cause arcing, as inductive loads force current through the connection. One particularly hazardous situation is a “loose neutral”. In this case, the neutral connection of a single or three-phase service is not properly connected. With balanced loads, the neutral conductor has no current flow, and thus the improper connection isn't noticed. When loads become unbalanced, the neutral current cannot flow properly through the improper connection, causing some phase voltages to rise, and others to fall, in proportion to the load imbalance. This may cause some phase voltage to rise to dangerous levels, creating significant risk for equipment damage, fire, and shock hazard. If the loose neutral is intermittent, and quickly alternating between low and high resistance, an arc hazard is also present. All these hazardous conditions contribute to a significant risk of fire and loss of life.
The typical way to test for a loose wiring problem is by inspection, or with sophisticated power quality equipment. Testing by inspection requires a trained electrician to torque every service entrance and main panel connection, a costly and risky task. Alternatively, expensive general-purpose power quality monitors (e.g. the PMI “S” series socket recorder) may be used to monitor the phase voltages, and IR temperature instruments may be used to estimate lug temperatures, which can indicate improper connections. These devices are expensive, and require trained personnel to install and analyze the data. In addition, these are generally short term checks—if a loose connection occurs after the spot-check or monitoring period, it will be undetected.